IT英语示例译文
数据通信系统
Data Communication Systems
There are five basic types of data communication system:
Off-line data transmission is simply the use of a telephone or similar link to transmit data without involving a computer system.The equipment used at both ends of such a link is not part of a computer, or at least does not immediately make the data available for computer process, that is, the data when sent and/or received are 'off-line'. This type of data communication is relatively cheap and simple.
Remote batch is the term used for the way in which data communication technology is used geographically to separate the input and /or output of data from the computer on which they are processed in batch mode.
On-line data collection is the method of using communications technology to provide input data to a computer as such input arises-the data are then stored in the computer(say on a magnetic disk)and processed either at predetermined intervals or as required.
Enquiry-response systems provide, as the term suggests, the facility for a user to extract information from a computer.The enquiry facility is passive, that is, does not modify the information stored.The interrogation may be simple, for example, 'RETRIEVE THE RECORD FOR EMPLOYEE NUMBER 1234' or complex.Such systems may use terminals producing hard copy and /or visual displays.
Real-time systems are those in which information is made available to and processed by a computer system in a dynamic manner so that either the computer may cause action to be taken to influence events as they occur(for example as in a process control application)or human operators may be influenced by the accurate and up-to-date information stored in the computer, for example as in reservation systems.
有五种基本的数据通信系统:
脱机数据传输是简单地利用电话或类似的链路来传输数据,不包括计算机系统。这样一条链路两端所使用的设备不是计算机的部件,或至少不是立刻把数据提供给计算机处理,即数据在发送或接收时是脱机的。这种数据通信相对来说比较便宜和简单。
远程批处理一词适用于这样一种方法:采用数据通信技术来使数据的输入和输出在地理上远离按批处理模式处理处理它们的计算机。
联机数据收集指的是用数据通信技术来向计算机即时提供刚产生的输入数据这种方法。数据于是存储在计算机里(比如磁盘上),并按预定时间间隔或者根据需要进行处理。
询问——应答系统,顾名思义,是为用户提供从计算机提取信息的功能。询问功能是被动的。也就是说,它不修改所存储的信息。提问可以很简单,例如:"检索雇员号码为1234的记录"也可以是复杂的。这类系统可能要使用能产生硬拷贝和(或)可视显示的终端。
实时系统是这样一类系统,其中计算机系统是在动态情况下取得和处理信息,以便可使计算机采取动作来影响正在发生的事件(比如在过程控制应用中)或者可通过存储在计算机里的准确且不断更新的信息来影响人(操作员),比如在预售系统中。
先进加密标准
Advanced Encryption Standard
For the past three years,the National Institute of Standards and Technology (NIST) has been working to develop a new encryption standard to keep government information secure.The organization is in the final stages of an open process of selecting one or more algorithms,or data-scrambling formulas,for the new Advanced Encryption Standard (AES) and plans to make adecision by late summer or early fall.The standard is slated to go into effect next year.
AES is intended to be a stronger,more efficient successor to Triple Data Encryption Standard(3DES),which replaced the aging DES,which was cracked in less than three days in July 1998.
“Until we have the AES,3DES will still offer protection for years to come.So there is no need to immediately switch over,”says Edward Roback, acting chief of the computer security division at NIST and chairman of the AES selection committee.“What AES will offer is a more efficient algorithm.It will be a federal standard,but it will be widely implemented in the IT community.”
According to Roback,efficiency of the proposed algorithms is measured by how fast they can encrypt and decrypt information,how fast they can present an encryption key and how much information they can encrypt.
The AES review committee is also looking at how much space the algorithm takes up on a chip and how much memory it requires.Roback says the selection of a more efficient AES will also result in cost savings and better use of resources.
“DES was designed for hardware implementations,and we are now living in a world of much more efficient software,and we have learned an awful lot about the design of algorithms,”says Roback.“When you start multiplying this with the billions of implementations done daily,the saving on overhead on the networks will be enormous.”
The process of selecting the algorithm for AES has been notable for its openness and transparency.This is a marked departure from the government's past inclination toward secrecy in discussing encryption standards,which led to the public cracking of DES after critics questioned the government's assertion that the standard was still secure.
NIST kicked off the selection process in September 1997.Conferences were held in August 1998 and March 1999; cryptographers from around the world discussed the algorithm candidates and helped narrow the list to 15 and then to five finalists: IBM's MARS; RSA Laboratories* RC6; Joan Daemen and Vincent Rijmen's Rijndael; Ross Andersen,Eli Baham and Lars Knudsen's Serpent; and Counterpane Labs* Twofish.
While most evaluators of the algorithms want to avoid complexity by selecting one to serve as a standard,there's a minority that wants to select more than one.
在过去三年中,(美国)国家标准与技术局(NIST)已在研究开发一种新的加密标准,以确保政府的信息安全。该组织目前正处于为新的先进加 密标准(AES)选择一龌蚣父鏊惴ɑ蚴荽蚵夜降目殴痰淖詈蠼锥危⒓苹谙哪┗蚯锍踝鞒鼍龆ā4吮曜寄诙髂晔凳?/p>
AES预定为比三层数据加密标准(3DES)更强、更高效的后续标准,3DES替代了老化的DES加密标准,DES在1998年7月在不到三天的时间内就 被破译了。
NIST计算机安全部的代理主管兼AES选择委员会主席Edward Roback说 :“在我们拥有AES之前,3DES还将在今后几年提供保护。所以没有必要马上转换。AES所提供的是一种更有效的算法。它将是一项联邦标准,但它将在IT界 广泛实施。”
据Roback称,提议中的算法的效率是通过对信息加密和解密有多快、给出加密密钥有多快以及能对多少信息加密等几个方面进行测量的。
AES评价委员会也要看算法占据芯片上多少空间和需要多少内存。Roback说,选择一个更高效的AES也会带来成本的节省和资源的更好利用。
Roback说:“DES是为硬件实现而设计的,而我们现在处于软件更高效的世界,我们对算法的设计有极多的了解。当我们开始大规模使用此算法,每天实现几十亿次的加密时,(算法带来的)网络开销的节省将是巨大的。”
为AES选择算法的过程是以其公开性和透明度称著。这标志着政府从以往讨论加密标准时倾向于保密的做法一刀两断,它导致了政府在断言DES 标准仍是安全时被公开破译。
NIST在1997年9月开始这个选择过程。1998年8月和 1999年3月召开了会议,来自全世界的密码专家讨论了候选的算法,帮助把算法缩小到15 个,最后到了5个:IBM的MARS算法,RSA实验室的RC6算法、Joan Daemen和Vincent Rijmen两人的Rijndael算法、Eli Baham和Lars Knudsen两人的Serpent算法以及Counterpane 实验室的Twofish算法。
大多数算法鉴定者都选择一个作标准以避免复杂性,但也有一小部分人要选择多个算法。
搜索引擎
Search Engines
Internet search tools fall into two camps: search engines, such as HotBot and AltaVista, and online directories, such as Yahoo and Lycos.The difference between the two is related to how they compile their site listings.Of course, there are exceptions to every rule.Some search utilities, such as Ask Jeeves, combine the search engine and directory approaches into a single package, hoping to provide users with the best of both worlds.
In directory-based search services, the Web site listings are compiled manually.For example, the everpopular Yahoo dedicates staff resources to accept site suggestions from users, review and categorize them, and add them to a specific directory on the Yahoo site.
You can usually submit your Web site simply by filling out an online form.On Yahoo, for example, you'll find submission information at www.yahoo.com/docs/info/include.html. Because human intervention is necessary to process, verify, and review submission requests, expect a delay before your site secures a spot in a directory-based search service.
On the flip side, search engines completely automate the compilation process, removing the human component entirely.
A software robot, called a spider or crawler, automatically fetches sites all over the Web, reading pages and following associated links.By design, a spider will return to a site periodically to check for new pages and changes to existing pages.
Results from spidering are recorded in the search engine's index or catalog.Given the wealth of information available on the Internet, it is not surprising that indexes grow to very large sizes.For example, the AltaVista index has recently been increased to top out at 350 million pages.This may seem like a mammoth number, but by all estimates it still represents less than 35 percent of all pages on the Web.
Because of the depth and breadth of information being indexed, there is usually a delay, sometimes up to several weeks, between the time a site has been“spidered”and when it appears in a search index.Until this two-step process has been completed, a site remains unavailable to search queries.
Finally, the heart of each search engine is an algorithm that matches keyword queries against the information in the index, ranking results in the order the algorithm deems most relevant.
Because the spiders, resulting indexes, and search algorithms of each search engine differ, so do the search results and rankings across the various search engines.This explains why a top 10 site in HotBot may not appear near the top of Alta Vista when the same keyword search criterion is entered.
In addition, many, but not all, search utilities also reference metatags—invisible HTML tags within documents that describe their content—as a way to control how content is indexed.As a result, proper use of metatags throughout a site can also boost search engine ranking.
因特网搜索工具分为两大阵营:搜索引擎,如HotBot和AltaVista,以及在线目录,如 Yahoo和Lycos。两者间的差别与它们如何编撰网站编目有关。当然,对任何规律都有例外。有些搜索实用程序,如Ask Jeeves,把搜索引擎和目录方法合并成单一的软件包,希望把这两个阵营中最好的东西提供给用户。
在基于目录的搜索服务中,Web网站编目是手工编撰的。比如一直流行的Yahoo就指定专门的人力资源来接受用户对网站的建议,并对建议进行评价和分类,再把它们加到Yahoo网站上特定目录中。
通常是通过简单地填写在线表格就能把你的网站信息提交给(搜索引擎)。例如,在Yahoo网站上,你可以在 www.yahoo.com/docs/info/include.htm1上找到提交信息。由于人工干预对处理、验证和评价提交请求是必要的,所以在网站在基于目录的搜索服务中捕捉到一处之前,可 望有些延迟。
另一方面,搜索引擎完全实现了编撰过程的自动化,彻底消除了人工干预。
一个叫做蜘蛛或爬虫的软件机器人自动地在整个Web上取出站点,阅读页面和跟随相关的链接。通过设计,蜘蛛可以周期性地返回到站点,检查新的页面和修改已有页面。
蜘蛛爬行得到的结果记录在搜索引擎的索引或目录中。已知了因特网上可资利用的信息的价值,对索引扩张到非常大的规模是不会感到惊讶的。例如,AltaVista的索引最近已增至3.5亿页而名列前茅。这个数字看来好像非常大,但总体估计它仅代表了Web上不足35%的页面。
由于已编索引的信息的深度与广度(非常大),所以通常在“蜘蛛爬行过”站点的时间与出现在搜索索引中的时间之间有一个延迟,有时多达几周。只有这两步的过程完成之后,站点才能供搜索查询使用。
最后,每个搜索引擎的心脏是一种算法,它将关键字查询与索引中的信息匹配起来,并按算法认为最有关联的顺序把结果列出。
由于每种搜索引擎的蜘蛛、产生的索引和搜索算法都是不一样的,所以在不同搜索引擎上的搜索结果和排列次序是不同的。这就解释了为什么当相同的关键字搜索准则输入进去时,HotBot中排在最前面的10个站点不会出现在 AltaVista中最前面的站点中。
此外,很多(但不是所有的)搜索实用程序也引用元标记(文档中用来描述其内容的、看不见的HTML标记),作为控制内容如何编索引的方法。因此,在整个站点中正确使用元标记也能提高(此站点)在搜索引擎中的排列名次。
E-mail地址中的符号@是什么意思
That little "a" with a circle curling around it that is found in email addresses is most commonly referred to as the "at" symbol.
小写字母a外加个圆圈,这一符号常出现在email(电子邮件)地址中,通常是作为"at"(在)的标记。
Surprisingly though, there is no official, universal name for this sign. There are dozens of strange terms to describe the @ symbol.
然而令人感到惊奇的是,这一标记居然没有官方的,通用的名称。有几十个奇怪的术语用来描绘@这一符号。
Before it became the standard symbol for electronic mail, the @ symbol was used to represent the cost or weight of something. For instance, if you purchased 6 apples, you might write it as 6 apples @ $1.10 each.
@这一符号在成为电子邮件的标准符号之前,曾被用来表示物品的单价或质量。例如,你买6只苹果。就可以写成"六只苹果,每只@$1.10,表示每只苹果1.10美元。
With the introduction of e-mail came the popularity of the @ symbol. The @ symbol or the "at sign" separates a person's online user name from his mail server address. For instance, joe@uselessknowledge.com. Its widespread use on the Internet made it necessary to put this symbol on keyboards in other countries that have never seen or used the symbol before. As a result, there is really no official name for this symbol.
随着电子邮件的使用,@这一符号越来越普及了。符号@或'at'标记将上网用户的姓名与其邮件的服务器地址分开。例如:joe@uselessknowledge.com。 这一符号在因特网上的广泛使用使得许多以前从未见过或使用过它的国家必须在它们的电脑键盘上加上这一符号键,结果造成这一符号并没有真正的官方名称。
The actual origin of the @ symbol remains an enigma.
@符号的确切起源仍然是谜。
History tells us that the @ symbol stemmed from the tired hands of the medieval monks. During the Middle Ages before the invention of printing presses, every letter of a word had to be painstakingly transcribed by hand for each copy of a published book. The monks that performed these long, tedious copying duties looked for ways to reduce the number of individual strokes per word for common words. Although the word "at" is quite short to begin with, it was a common enough word in texts and documents that medieval monks thought it would be quicker and easier to shorten the word "at" even more. As a result, the monks looped the "t" around the "a" and created it into a circle-eliminating two strokes of the pen.
历史告诉我们,@这一符号起源于中世纪僧侣疲劳的双手。中世纪时印刷机尚未发明,要出版一本书,每一个单词的每一个字母都得用手工辛苦的刻出来。从事这项长时间辛苦誊写刻画的僧侣们就开始寻找减少每一个常用字笔画数的方法。虽然"at"这一单词开始写起来很短,但它在文本和文件中频繁出现。中世纪的僧侣们就想到如果能进一步简化它,就可以写起来更快更容易。结果,僧侣们就在a四周画了一个圈,从而省却了字母"t"的两个笔划。
了解到底什么是多媒体
The answer is neither simple nor easy. Multimedia is the combination of computer and video technology. Multimedia really just two media sound and pictures, or in today's term, audio and video. Multimedia itself has its binary aspects. As with all modern technologies, it is made from a mix of hardware and software, machine and ideas. More importantly, you can conceptually divide technology and function of multimedia into control systems and information. The enabling force behind multimedia is digital technology. Multimedia represents the convergence of digital control and digital media---the PC as the digital control system and the digital media being today's most advanced form of audio and video storage and transmission. In fact, some people see multimedia simply as the marriage of PCs and video. PC power has reached a level close to that needed for procession television and sound data streams in real time, multimedia was born. Multimedia PC needs to be more powerful than mainstream computer---at least the multimedia PC defines the mainstream. Among contemporary PCs, about the only things that separate an ordinary computer from multimedia are a soundboard and a CD- ROM driver. The CD serves as multimedia 's chief storage and exchange medium. Without the convenient CD, the PC industry would lack a means of distributing the hundreds of megabytes of audio, visual, and textual data that make up today's multimedia titles. Without CD, you couldn't buy multimedia because publishers have no way of getting it to you.
So what is multimedia? By now you should agree that multimedia isn't any one thing but a complex entity that involves the many things: hardware, software, and the interface where they meet. But we've forgotten the most important thing that multimedia involves: you. Yeah, sure. With multimedia, you don' t have to be a passive recipient. You can control. You can interact. You can make it do what you want it to do. It means you can tailor a multimedia presentation to your own needs. You can cut through the chaff and dig directly into the important data in a report, pull together reports and video clips from around the world that interest you. That's the strength of multimedia and what distinguishes it from traditional media like books and television.
What does multimedia do? It presents information, shares ideas and elicits emotions. It enables you to see, hear, and understand the thoughts of others. In other words, it is a form of communication.
要回答这个问题不那么容易。多媒体是计算机和视频技术的结合,实际上它是两个媒体;声音和图像,或者用现在的术语:音响和电视。多媒体本身有两个方面,和所有现代技术一样它是由硬件和软件,或机器和思想混合组成。可以将多媒体技术和功能在概念上区分为控制系统和信息。 多媒体之所以能够实现是依靠数字技术。多媒体代表数字控制和数字媒体的汇合,电脑是数字控制系统,而数字媒体是当今音频和视频最先进的存储和传播形式。事实上有人就简单地认为多媒体是电脑和电视的结合。电脑的能力达到实时处理电视和声音数据流的水平,这时多媒体就诞生了。多媒体电脑需要具有比主流电脑更强的能力,多媒体电脑决定了主流电脑的发展。区别普通电脑和多媒体电脑的主要东西是声卡和只读光盘驱动器。光盘是多媒体的主要存储和交换媒体。没有这种方便的光盘,电脑工业就无法销售构成多媒体节目的几百兆字节的音频、可视的和文字的数据,你也无法买到多媒体。
现在可以回答什么是多媒体。它不只是一件东西,而是包括许多东西的复杂的组合:硬件、软件和这两者相遇时的界面。不,我们还忘了一件最重要的事情.多媒体还包括你。咳,就是!对于多媒体,你不再是一个被动的观众,你可以控制,可以交互作用,可以让它按你的需要去做。在一个报告中,你可以不管那些无用的东西而直接进入重要的数据,可以将感兴趣的全世界的报告和图片收集汇编到一起。这就是多媒体的力量和它与传统媒体(如书本和电视)的区别所在。
多媒体能做什么?它展示信息、交流思想和抒发情感。它让你看到、听到和理解其他人的思想。也就是说,它是一种通讯的方式。
名词解释:base address
base address 基址:
the part of a two-part memory address that remains constant and provides a reference point from which the location of a byte of data can be calculated. a base address is accompanied by an offset value that is added to the base to determine the exact location(the absolute address)of the information. the concept is similar to a street address system . for example, "2010 main street " plus an offset(10from the beginning of the block ).base address are known as segment address in IBM pcs and compatibles; data in these computers is identified by its position as a relative offset the start of the segment.
保持恒定的两部分内存地址的一部分并提供一个基准点,从这里可以计算一个字节数据的位置。基址伴随着一个加到基上的偏移值来确定信息准确的位置(绝对地址)。这一概念与街道地址系统雷同。例如:“大街2010号”由基(大街2000街段)加上偏移值(从街段开始的10号)。在IBMPC和兼容机中的数据按其相对于由段开始的相对偏移位置被识别。
常见Internet术语表(Ⅰ)
ADN
(Advanced Digital Network) -- Usually refers to a 56Kbps leased-line.
Applet
A small Java program that can be embedded in an HTML page. Applets differ from full-fledged Java applications in that they are not allowed to access certain resources on the local computer, such as files and serial devices (modems, printers, etc.), and are prohibited from communicating with most other computers across a network. The current rule is that an applet can only make an Internet connection to the computer from which the applet was sent.
Archie
A tool (software) for finding files stored on anonymous FTP sites. You need to know the exact file name or a substring of it.
ARPANet
(Advanced Research Projects Agency Network) -- The precursor to the Internet. Developed in the late 60’s and early 70’s by the US Department of Defense as an experiment in wide-area-networking that would survive a nuclear war.
ASCII
(American Standard Code for Information Interchange) -- This is the de facto world-wide standard for the code numbers used by computers to represent all the upper and lower-case Latin letters, numbers, punctuation, etc. There are 128 standard ASCII codes each of which can be represented by a 7 digit binary number: 0000000 through 1111111.
Backbone
A high-speed line or series of connections that forms a major pathway within a network. The term is relative as a backbone in a small network will likely be much smaller than many non-backbone lines in a large network.
Bandwidth
How much stuff you can send through a connection. Usually measured in bits-per-second. A full page of English text is about 16,000 bits. A fast modem can move about 15,000 bits in one second. Full-motion full-screen video would require roughly 10,000,000 bits-per-second, depending on compression.
Baud
In common usage the baud rate of a modem is how many bits it can send or receive per second. Technically, baud is the number of times per second that the carrier signal shifts value - for example a 1200 bit-per-second modem actually runs at 300 baud, but it moves 4 bits per baud (4 x 300 = 1200 bits per second).
BBS
(Bulletin Board System) -- A computerized meeting and announcement system that allows people to carry on discussions, upload and download files, and make announcements without the people being connected to the computer at the same time. There are many thousands (millions?) of BBS’s around the world, most are very small, running on a single IBM clone PC with 1 or 2 phone lines. Some are very large and the line between a BBS and a system like CompuServe gets crossed at some point, but it is not clearly drawn.
Binhex
(BINary HEXadecimal) -- A method for converting non-text files (non-ASCII) into ASCII. This is needed because Internet e-mail can only handle ASCII.
Bit
(Binary DigIT) -- A single digit number in base-2, in other words, either a 1 or a zero. The smallest unit of computerized data. Bandwidth is usually measured in bits-per-second.
BITNET
(Because It’s Time NETwork (or Because It’s There NETwork)) -- A network of educational sites separate from the Internet, but e-mail is freely exchanged between BITNET and the Internet. Listservs?, the most popular form of e-mail discussion groups, originated on BITNET. BITNET machines are usually mainframes running the VMS operating system, and the network is probably the only international network that is shrinking.
Bps
(Bits-Per-Second) -- A measurement of how fast data is moved from one place to another. A 28.8 modem can move 28,800 bits per second.
Browser
A Client program (software) that is used to look at various kinds of Internet resources.
BTW
(By The Way) -- A shorthand appended to a comment written in an online forum.
Byte
A set of Bits that represent a single character. Usually there are 8 Bits in a Byte, sometimes more, depending on how the measurement is being made.
posted on 2007-04-29 15:35 sharewind 阅读(1004) 评论(0) 编辑 收藏 举报